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Nature Jun 2003
Topics: Animals; Antigens, Protozoan; Carbohydrates; Female; Humans; Leishmania; Male; Parasitic Diseases; Protozoan Vaccines; Trypanosoma brucei brucei
PubMed: 12789309
DOI: 10.1038/423580a -
Clinical Microbiology Reviews Apr 2001Leishmaniae are obligatory intracellular protozoa in mononuclear phagocytes. They cause a spectrum of diseases, ranging in severity from spontaneously healing skin... (Review)
Review
Leishmaniae are obligatory intracellular protozoa in mononuclear phagocytes. They cause a spectrum of diseases, ranging in severity from spontaneously healing skin lesions to fatal visceral disease. Worldwide, there are 2 million new cases each year and 1/10 of the world's population is at risk of infection. To date, there are no vaccines against leishmaniasis and control measures rely on chemotherapy to alleviate disease and on vector control to reduce transmission. However, a major vaccine development program aimed initially at cutaneous leishmaniasis is under way. Studies in animal models and humans are evaluating the potential of genetically modified live attenuated vaccines, as well as a variety of recombinant antigens or the DNA encoding them. The program also focuses on new adjuvants, including cytokines, and delivery systems to target the T helper type 1 immune responses required for the elimination of this intracellular organism. The availability, in the near future, of the DNA sequences of the human and Leishmania genomes will extend the vaccine program. New vaccine candidates such as parasite virulence factors will be identified. Host susceptibility genes will be mapped to allow the vaccine to be targeted to the population most in need of protection.
Topics: Animals; History, 20th Century; Humans; Leishmania; Leishmaniasis; Protozoan Vaccines
PubMed: 11292637
DOI: 10.1128/CMR.14.2.229-243.2001 -
Parasitology Research Jun 2017Toxoplasmosis is an infectious disease caused by the intracellular parasite Toxoplasma gondii that affects about one third of the world's population. The diagnosis of... (Review)
Review
Toxoplasmosis is an infectious disease caused by the intracellular parasite Toxoplasma gondii that affects about one third of the world's population. The diagnosis of this disease is carried out by parasite isolation and host antibodies detection. However, the diagnosis presents problems in regard to test sensitivity and specificity. Currently, the most effective T. gondii treatment is a combination of pyrimethamine and sulfadiazine, although both drugs are toxic to the host. In addition to the problems that compromise the effective diagnosis and treatment of toxoplasmosis, there are no reports or indications of any vaccine capable of fully protecting against this infection. Nanomaterials, smaller than 1000 nm, are currently being investigated as an alternative tool in the management of T. gondii infection. This article reviews how recent nanotechnology advances indicate the utility of nanomaterials in toxoplasmosis diagnosis, treatment, and vaccine development.
Topics: Animals; Humans; Nanostructures; Protozoan Vaccines; Toxoplasma; Toxoplasmosis
PubMed: 28477099
DOI: 10.1007/s00436-017-5458-2 -
Expert Review of Vaccines Jun 2009Toxoplasmosis, caused by an intracellular protozoan parasite, Toxoplasma gondii, is widespread throughout the world. The disease is of major medical and veterinary... (Review)
Review
Toxoplasmosis, caused by an intracellular protozoan parasite, Toxoplasma gondii, is widespread throughout the world. The disease is of major medical and veterinary importance, being a cause of congenital disease and abortion in humans and domestic animals. In addition, recently it has gained importance owing to toxoplasma encephalitis in AIDS patients. In the last few years, there has been considerable progress towards the development of a vaccine for toxoplasmosis, and a vaccine based on the live-attenuated S48 strain was developed for veterinary uses. However, this vaccine is expensive, causes side effects and has a short shelf life. Furthermore, this vaccine may revert to a pathogenic strain and, therefore, is not suitable for human use. Various experimental studies have shown that it may be possible to develop a vaccine against human toxoplasmosis. Recent progress in knowledge of the protective immune response generated by T. gondii and the current status of development of a vaccine for toxoplasmosis are highlighted.
Topics: Animals; Biomedical Research; Humans; Protozoan Vaccines; Toxoplasma; Toxoplasmosis
PubMed: 19485758
DOI: 10.1586/erv.09.27 -
Journal of Veterinary Internal Medicine 2013This review assesses the efficacy of whole cell Tritrichomonas foetus vaccine to prevent and treat trichomoniasis in beef cattle. Three databases were searched in June... (Meta-Analysis)
Meta-Analysis Review
This review assesses the efficacy of whole cell Tritrichomonas foetus vaccine to prevent and treat trichomoniasis in beef cattle. Three databases were searched in June 2012. Eligible studies compared infection risk, open risk, and abortion risk in heifers or infection risk in bulls that received vaccine compared with no vaccine. Study results were extracted, summary effect measures were calculated, and the quality of the evidence was assessed. From 334 citations identified, 10 were relevant to the review. For heifers, there was limited evidence of moderate quality to assess the impact of vaccination on infection risk (RR, 0.89; P = .16; 95% CI, 0.76-1.05; 6 randomized and 4 nonrandomized studies; 251 animals) and open risk (RR, 0.80; P = .06; 95% CI, 0.63-1.01; 6 randomized and 5 nonrandomized studies; 570 animals). The quality of the body of work describing the impact of vaccination on abortion risk was low (summary RR, 0.57; P = .0003; 95% CI, 0.42-0.78; 3 randomized and 2 nonrandomized studies; 176 animals). The quality of evidence was very low for duration of infection (mean difference, -23.42; P = .003; 95% CI, -38.36 to -7.85; 2 randomized and 3 nonrandomized studies; 163 animals). Although the summary effect measures suggest a benefit to vaccination, due to publication bias the effect reported here is likely an over estimate of efficacy. For bull-associated outcomes, the evidence base was low or very low quality.
Topics: Animals; Cattle; Cattle Diseases; Protozoan Infections, Animal; Protozoan Vaccines; Tritrichomonas
PubMed: 23701212
DOI: 10.1111/jvim.12112 -
Trends in Parasitology Nov 2010A series of studies over 20 years mapped resistance to toxoplasmic encephalitis in mice to major histocompatibility complex class I (MHC I) and ultimately, more... (Review)
Review
A series of studies over 20 years mapped resistance to toxoplasmic encephalitis in mice to major histocompatibility complex class I (MHC I) and ultimately, more precisely the Ld region. This is consistent with contemporary functional studies that demonstrated a protective role for CD8(+) T cells. Recent studies have demonstrated that the Ld gene product presents a number of immunodominant Toxoplasma gondii-derived peptides in the murine models, providing a paradigm for vaccine design. The almost complete sequencing of the genomes of the predominant strains of T. gondii in conjunction with the development of predictive binding algorithms for MHC I peptides in humans now offers a new opportunity for vaccine development against this medically important pathogen.
Topics: Animals; CD8 Antigens; Genes, MHC Class I; H-2 Antigens; Humans; Mice; Oligopeptides; Protozoan Vaccines; T-Lymphocytes, Cytotoxic; Toxoplasma; Toxoplasmosis, Animal
PubMed: 20580611
DOI: 10.1016/j.pt.2010.06.004 -
Trends in Parasitology Jun 2004
Review
Topics: Animals; Apoptosis; Eukaryota; Host-Parasite Interactions; Protozoan Infections; Protozoan Vaccines; Vaccines, Attenuated
PubMed: 15147679
DOI: 10.1016/j.pt.2004.04.004 -
Frontiers in Immunology 2019Parasites, including African trypanosomes, utilize several immune evasion strategies to ensure their survival and completion of their life cycles within their hosts. The... (Review)
Review
Parasites, including African trypanosomes, utilize several immune evasion strategies to ensure their survival and completion of their life cycles within their hosts. The defense factors activated by the host to resolve inflammation and restore homeostasis during active infection could be exploited and/or manipulated by the parasites in an attempt to ensure their survival and propagation. This often results in the parasites evading the host immune responses as well as the host sustaining some self-inflicted collateral tissue damage. During infection with African trypanosomes, both effector and suppressor cells are activated and the balance between these opposing arms of immunity determines susceptibility or resistance of infected host to the parasites. Immune evasion by the parasites could be directly related to parasite factors, (e.g., antigenic variation), or indirectly through the induction of suppressor cells following infection. Several cell types, including suppressive macrophages, myeloid-derived suppressor cells (MDSCs), and regulatory T cells have been shown to contribute to immunosuppression in African trypanosomiasis. In this review, we discuss the key factors that contribute to immunity and immunosuppression during infection, and how these factors could aid immune evasion by African trypanosomes. Understanding the regulatory mechanisms that influence resistance and/or susceptibility during African trypanosomiasis could be beneficial in designing effective vaccination and therapeutic strategies against the disease.
Topics: Animals; Humans; Immune Evasion; Macrophages; Myeloid-Derived Suppressor Cells; Protozoan Vaccines; T-Lymphocytes, Regulatory; Trypanosoma congolense; Trypanosomiasis, African
PubMed: 31824512
DOI: 10.3389/fimmu.2019.02738 -
Parasitology Oct 2009Eimeria spp. are the causative agents of coccidiosis, a major disease affecting many intensively-reared livestock, especially poultry. The chicken is host to 7 species... (Review)
Review
Eimeria spp. are the causative agents of coccidiosis, a major disease affecting many intensively-reared livestock, especially poultry. The chicken is host to 7 species of Eimeria that develop within intestinal epithelial cells and produce varying degrees of morbidity and mortality. Control of coccidiosis by the poultry industry is dominated by prophylactic chemotherapy but drug resistance is a serious problem. Strongly protective but species-specific immunity can be induced in chickens by infection with any of the Eimeria spp. At the Institute of Animal Health in Houghton, UK in the 1980s we showed that all 7 Eimeria spp. could be stably attenuated by serial passage in chickens of the earliest oocysts produced (i.e. the first parasites to complete their endogenous development) and this process resulted in the depletion of asexual development. Despite being highly attenuated, the precocious lines retained their immunizing capacity. Subsequent work led to the commercial introduction of the first live attenuated vaccine, Paracox, that has now been in use for 20 years. As much work still remains to be done before the development of recombinant vaccines becomes a reality, it is likely that reliance upon live, attenuated vaccines will increase in years to come.
Topics: Animals; Chickens; Coccidiosis; Eimeria; Poultry Diseases; Protozoan Vaccines; Vaccination; Vaccines, Attenuated
PubMed: 19523251
DOI: 10.1017/S0031182009006349 -
Parasite Immunology Jul 2006The Eimeria species, causative agents of the disease coccidiosis, are genetically complex protozoan parasites endemic in livestock. Drug resistance remains commonplace... (Review)
Review
The Eimeria species, causative agents of the disease coccidiosis, are genetically complex protozoan parasites endemic in livestock. Drug resistance remains commonplace among the Eimeria, and alternatives to chemotherapeutic control are being sought. Vaccines based upon live formulations of parasites are effective, but production costs are high, stimulating demand for a recombinant subunit vaccine. The identity of antigens suitable for inclusion in such vaccines remains elusive. Selection of immunoprotective antigens of the Eimeria species as vaccine candidates based upon recognition by the host immune system has been unsuccessful, obscured by the considerable number of molecules that are immunogenic but not immunoprotective. This is a common problem which characterizes work with most eukaryotic parasites. The identification of a selective criterion to directly access genetic loci that encode immunoprotective antigens of Eimeria maxima using a mapping strategy based upon parasite genetics, immune selection and DNA fingerprinting promises to revolutionize the process of antigen discovery. Linkage analyses of DNA markers amplified from populations of recombinant parasites defined by an ability to escape parent-specific deleterious selection by strain-specific immunity and chemotherapy has revealed four discrete regions within the E. maxima genome linked to escape from a protective immune response. These regions now form the basis of detailed study to identify antigens as candidates for inclusion in future vaccination strategies.
Topics: Animals; Antigens, Protozoan; Chickens; Coccidiosis; Eimeria; Protozoan Vaccines; Vaccines, Synthetic
PubMed: 16842267
DOI: 10.1111/j.1365-3024.2006.00831.x